Which of the following represents the wavelength of a wave?
a
b
c
d

According to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does maria's voyage take according to samir?

For those who need theses answers i just took the test and got everyone of them

When the acceleration of a mass on a spring is zero, the velocity is at a (fill in the blank) . when the velocity of a mass on a spring is zero, the acceleration is at a (fill in the blank) .